Sterile pharmaceutical solutions, such as 5 percent dextrose, normal saline and the like, are supplied to hospitals for infusion into a patient's veins from a container hanging above the patient. The sterile liquid flows by gravity through a tubular administration set connected at one end to the container and at an opposite end to a venous needle in the patient.
Such containers are frequently formed of thermoplastic material, and will include a neck portion having one or more ports or openings extending through the neck portion. Such ports may be commonly hermetically sealed to provide sterile sealed contents to the container.
It is desirable that the port be in a sterile environment. Difficulty is experienced with thermoplastic closures bonded directly to the bottle neck in that excessive force is required to fracture or remove the closure. Frangible thermoplastic closures are known wherein a frangible section is provided around its base defined by a series of slots or cuts in the closure; such closure does not maintain the sterile environment within the closure. An example of this type of closure is shown in McPhee U.S. Pat. No. 3,904,060. Thermoplastic closures are also known which are bonded entirely around their base to provide a hermetic seal; a frangible section may be provided adjacent the seal. The frangible sections commonly require flexural shear force to fracture and the required force frequently is too great for many applications. An example of a closure requiring a separate threaded screw-jack ring to attain flexural shear force to fracture the frangible section is shown in Choksi U.S. Pat. No. 3,923,182.